1984 70 horse Yamaha overheating ?
 

My outboard overheat alarm goes off when backtrolling for a short
period of time. After 5 mins or so it runs fine again and the alarm
never sounds when running at normal speeds. Where should I start a new
water pump the thermostat or a clogged passige way. Im in a bad spot as
salmon season opens tomorrow. Even if I can get the parts today is
changeing the water pump to much to tackle for an average joe at home ?
Any advise or help I would apreciate as Im obligated to friends and a
10 year old boy to fish tomorrow morning.

1984 70 horse Yamaha overheating ?
 

Overheating at idle is often the water pump. It may be wearing out and not
delivering enough water at low speed. When you go faster the rpm make up
for the worn out water pump.

"oneslikfish" wrote in message
oups.com...
My outboard overheat alarm goes off when backtrolling for a short
period of time. After 5 mins or so it runs fine again and the alarm
never sounds when running at normal speeds. Where should I start a new
water pump the thermostat or a clogged passige way. Im in a bad spot as
salmon season opens tomorrow. Even if I can get the parts today is
changeing the water pump to much to tackle for an average joe at home ?
Any advise or help I would apreciate as Im obligated to friends and a
10 year old boy to fish tomorrow morning.

1984 70 horse Yamaha overheating ?
 

"oneslikfish" wrote in message
oups.com...
My outboard overheat alarm goes off when backtrolling for a short
period of time. After 5 mins or so it runs fine again and the alarm
never sounds when running at normal speeds. Where should I start a new
water pump the thermostat or a clogged passige way.



On a 22 year old Yamaha, especially if used in sal****er, clogged
passageways are usually associated with high speed overheat problems, not at
idle. Most likely a worn water pump assembly and a corroded thermostat are
the causes and should be replaced first. Clean out any debris or corrosion
in the thermostat cavity and look for "eaten away" areas on the aluminum
castings. Replace the waterpump as a complete kit, not just the impeller.
There is also a possibility of a head gasket leak on a motor that old but
don't try to take things apart that you don't have to at the moment.

Be sure to let us know what fixes the problem

Bill Grannis
service manager

1984 70 horse Yamaha overheating ?
 

Billgran wrote:

"oneslikfish" wrote in message
oups.com...
My outboard overheat alarm goes off when backtrolling for a short
period of time. After 5 mins or so it runs fine again and the alarm
never sounds when running at normal speeds. Where should I start a new
water pump the thermostat or a clogged passige way.



On a 22 year old Yamaha, especially if used in sal****er, clogged
passageways are usually associated with high speed overheat problems, not at
idle. Most likely a worn water pump assembly and a corroded thermostat are
the causes and should be replaced first. Clean out any debris or corrosion
in the thermostat cavity and look for "eaten away" areas on the aluminum
castings. Replace the waterpump as a complete kit, not just the impeller.
There is also a possibility of a head gasket leak on a motor that old but
don't try to take things apart that you don't have to at the moment.

Be sure to let us know what fixes the problem

Bill Grannis
service manager 22 year old motor but completely rebuilt 5 years ago.Thermostat checks out good, cavity clean, engine never used in salt water. I am suspecting some sort of blockage or pressure control type of valve that is not functioning correctly. A diagram, schematic, or picture would help me tremendously right now. Do you no of a freeone I could look at on the net ?

1984 70 horse Yamaha overheating ?
 

oneslikfish wrote:
Billgran wrote:

"oneslikfish" wrote in message
oups.com...
My outboard overheat alarm goes off when backtrolling for a short
period of time. After 5 mins or so it runs fine again and the alarm
never sounds when running at normal speeds. Where should I start a new
water pump the thermostat or a clogged passige way.



On a 22 year old Yamaha, especially if used in sal****er, clogged
passageways are usually associated with high speed overheat problems, not at
idle. Most likely a worn water pump assembly and a corroded thermostat are
the causes and should be replaced first. Clean out any debris or corrosion
in the thermostat cavity and look for "eaten away" areas on the aluminum
castings. Replace the waterpump as a complete kit, not just the impeller.
There is also a possibility of a head gasket leak on a motor that old but
don't try to take things apart that you don't have to at the moment.

Be sure to let us know what fixes the problem

Bill Grannis
service manager 22 year old motor but completely rebuilt 5 years ago.Thermostat checks out good, cavity clean, engine never used in salt water. I am suspecting some sort of blockage or pressure control type of valve that is not functioning correctly. A diagram, schematic, or picture would help me tremendously right now. Do you no of a freeone I could look at on the net ?

1984 70 horse Yamaha overheating ?
 

"oneslikfish" wrote in message


Even if I can get the parts today is
changeing the water pump to much to tackle for an average joe at home ?


Could be,

Most of those old yamaha engines had a problem where the impeller is
so reliable, people never change them out. Corrosion then takes over and
removing the lower unit *could* be a chore if your bolts are frozen.

Otherwise, Its probably about an hour job. I usually put just a smidge of
white lithium grease on the new impeller just to help it fit back in. Just
enough
to keep the rubber from being sticky.

db